HDDs are common information storage devices. With improvements in recording density of magnetic HDDs, there has been a demand for improving the performance of magnetic heads and magnetic recording media. In a magnetic hard disk drive, a magnetic head is embedded in a slider that flies above the surface of a magnetic recording medium.
Recently, a technology so-called thermal assisted magnetic recording has been proposed, and a thermal assisted magnetic head also has been put to use. The technology uses a magnetic recording medium having high coercivity. When writing data, a write magnetic field and heat are applied almost simultaneously to the area of the magnetic recording medium where to write data, so that the area rises in temperature and drops in coercivity for data writing. The area where data is written subsequently falls in temperature and rises in coercivity to increase the thermal stability of magnetization.
Commonly, the heat source comes from the thermal assisted magnetic head. FIG. 1a shows a perspective view of a conventional thermal assisted magnetic head 100. The thermal assisted magnetic head 100 includes a slider body 110 having an air bearing surface (ABS) (not shown, under) processed so as to provide an appropriate flying height and a light source unit 130 mounted on the slider body 110. The slider body 110 includes a bottom surface 112 opposite the ABS, a trailing edge 113 where read and write elements 115 are embedded, and a leading edge (not shown, back) opposite the trailing edge 113. The light source unit 130 is mounted on the position where the write elements are embedded via a bonding layer. The light source unit 130 includes a laser diode 131 located near the write element and a mounting base 132 for supporting the laser diode 131. The mounting base 132 is bonded to the slider body 110 by using a solder layer, for example. The laser diode 131 emits a laser light to a portion of the magnetic recording medium, which reduces the medium's coercivity. After that, writing is performed by applying write magnetic field to the heated portion; therefore the writing operation is facilitated.
FIG. 1b shows a conventional manufacturing method of a thermally-assisted magnetic head. In the process of manufacturing the thermally-assisted magnetic head including the laser diode, the unit substrate and the slider as described above, it is important that the unit substrate be accurately positioned with respect to the slider and secured thereto so that emitted light from the laser diode will be accurately incident on the incidence end of the waveguide.
U.S. Patent Application Publication No. 2011/0228650 A1 discloses a positioning and bonding method that allows the unit substrate to be positioned with respect to the slider and secured thereto in the following manner. In the positioning and bonding method, emitted light from the laser diode is allowed to be incident on the incidence end of the waveguide, the intensity of light emitted from the emitting end of the waveguide is detected, and the unit substrate is positioned with respect to the slider so that the aforementioned intensity becomes maximum. Subsequently, the unit substrate is irradiated with heating laser light that is projected to pass through the unit substrate, so that the solder interposed between the slider and the unit substrate is heated and melted by the heating laser light. After that, the irradiation with the heating laser light is stopped to solidify the solder to thereby allow the unit substrate to be secured to the slider. FIG. 1c shows the irradiating time and the irradiating power during the bonding process.
Now, problems with the positioning and bonding method above will be described. In the method above, there may occur misalignment of the unit substrate with respect to the slider in the process of melting and then solidifying the solder to thereby secure the unit substrate to the slider.
Accordingly, it is desired to provide improved method of manufacturing a thermally-assisted magnetic head to overcome the above-mentioned drawbacks.